Exhaust gas turbochargers for internal combustion engines are known where the turbocharger is driven by the energy available in the exhaust gases of the engine. Such a turbocharger, in turn, supplies engine charge air to the internal combustion engine to which the turbocharger is connected. In an internal combustion engine, the exhaust energy is a function of the power output and therefore proportional to the engine speed for the full load fueling rate. Thus, at the lower end of the engine speed range, there is little energy in the exhaust gas and the power available to the turbocharger is low. The air supplied to the engine by the turbocharger is consequently low in quantity and pressure under these conditions.
The use of a turbocharger permits a smaller engine to deliver substantial horsepower at a considerable weight savings which will become increasingly attractive for future vehicles where gasoline economy is at a premium. A supercharger is only needed for maximum power for passenger vehicles, and thus, would be idle most of the time. At low engine speeds, the energy in the exhaust gases is insufficient to provide immediate acceleration of the turbocharger, and consequently of the vehicle.
With small lightweight cars for the future, the accessory power requirements will be a larger percentage of the power required to drive the vehicle. Accessory drives which will limit the upper speed of the accessories driven by the vehicle engine will achieve a power saving and are presently under consideration in the automotive industry. The present invention solves the problems of the vehicle accessory drive and acceleration of the vehicle from low speeds.
The present invention comprehends the provision of a combined exhaust gas turbine, supercharger and accessory drive for a vehicle engine which will utilize engine power to drive the supercharger for instant acceleration from low speeds, and will use the exhaust gas turbine to drive the vehicle accessories at substantially constant speed where sufficient energy is available from the turbine. At almost all times, there will be at least some energy return from the exhaust gas to help share the accessory load.
The present invention also comprehends the provision of a combined exhaust gas turbine, supercharger and accessory drive in conjunction with a vehicle engine wherein the exhaust gas turbine is mechanically connected to the supercharger through suitable gearing, a one-way clutch and a friction clutch. An accessory drive shaft is connected to an engine driven pulley through a centrifugally unloading clutch, and the accessory drive shaft is connected through an additional gear to the power transmission between the exhaust gas turbine and the supercharger. The one-way clutch prevents power from the engine to be used to accelerate the exhaust gas turbine.
The present invention further comprehends the provision of a combined exhaust gas turbine, supercharger and accessory drive wherein the drive from the exhaust gas turbine is split with part of the drive being imparted to the supercharger and part to the accessory drive. The exhaust gas turbine provides the power necessary to drive both the supercharger and the accessories at high engine power levels.
Further objects are to provide a construction of maximum simplicity, efficiency, economy and ease of assembly and operation, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.